1. Field of the Invention
The present invention relates to a cytotoxic assay of various kinds of specimens, such as chemical compounds and heavy metals. Furthermore, the present invention relates to a new established cell line expected to be used in the diagnosis of viral infection disease of sturgeon.
2. Background Art
Heretofore the toxicity tests of quality of various specimens such as chemical compounds or heavy metals (zinc, cadmium, copper, arsenic, cobalt, molybdenum, nickel, lead, selenium, chromium, tin, and mercury and so on) have been done with individual animals. However, the method using the individual animals suffers a problem of too much time and expense as well as that from a viewpoint of animal protection. In late years, therefore, toxicity assays that utilize established cell lines (culture cells) (i.e., cytotoxic assays), have been considered.
It is desirable to perform the toxicity test of a specimen in an aqueous environment with an established cell line derived from a fish origin. The toxicity assays using RTG-2 cells which are cells of a fibroblastic established cell line originated from a rainbow trout ovary and FHM cells which are cells of an epithelial established cell line originated from fathead minnow have been considered. However, these methods are not adequate in an aspect of sensitivity. In addition, there is a problem that a growth rate is late and a growth temperature range is small as for the RTG-2 cell, which can not be always satisfactory in an aspect of convenience.
In late years, aquaculture skills continue a remarkable development in increasing the number of fish species which can be cultivated and improving the stabilities in supply. On the other hand, there is a problem of the death of a culture fish by an infection disease caused by, such as bacteria or viruses. In particular, the fact is that there is no measure effective to such a problem even though viral infection disease after leads to a large quantity of deaths. For viral infection disease, it becomes important how early it is checked.
For the diagnosis of viral infection, established cell lines having sensitivities against the virus that is responsible for viral infection in fishes are indispensable. As to the established cell line of fish origin, many established cell lines have been reported since RTG-2 cells which are of a fibroblastic established cell line originated from a rainbow trout ovary were established. However, many of these established cell lines are derived from fibroblastic origins but not epithelial origins. That is, most of them are isolated, cultured and established from limited fish species such as salmon and carp. Consequently, at present, the diagnosis of viral infection or the isolation of virus itself are not always smoothly performed about a various kinds of fish species.
By the way, sturgeon is the ancient species that has lived for about 300000000 years, but its egg is valued high as caviar, and, also its meat has high utility value as edible, thus it is expected as future culture object fish. In such an aspect, there is an indispensable need for established cell lines to check viral infection disease of sturgeon. However, only a few reports have been published for the established cell lines of sturgeon, although for example, there is a report about the established cell lines of white sturgeon grouped in the genus Acipenser in “Transactions of the American Fisheries Society” 120: 528–534, 1991. Therefore, it is very important to establish a new established cell line expected to be used for the diagnosis of viral infection disease of sturgeon. The establishment of such a new established cell line will lead to a great advantage in the production of vaccine effective to viral infection disease of sturgeon and at the time of the cytotoxic tests of chemical compounds, heavy metals or the like.